Patent application title: DOUBLE-SIDED RECORDING APPARATUS

Abstract:

A double-sided image forming apparatus includes a line-recording
front-side image forming apparatus and a line-recording rear-side image
forming apparatus which are arranged in a transportation direction of a
recording medium, in which each of the front-side image forming apparatus
and the rear-side image forming apparatus includes a drum, a roller
having a smaller diameter than the drum, an endless belt wound around the
drum and the roller, a driving power source which transports the belt by
rotating the drum, and a line-recording recording unit placed to face an
outer circumferential surface of the drum so as to be able to perform
recording with respect to the recording medium which is laid on the outer
circumferential surface of some portion of the belt which is wound around
the drum.

Claims:

1. A double-sided image forming apparatus comprising:a line-recording
front-side image forming apparatus; anda line-recording rear-side image
forming apparatus, the line-recording front-side image forming apparatus
and the line-recording rear-side image forming apparatus arranged in a
transportation direction of a recording medium,wherein each of the
front-side image forming apparatus and the rear-side image forming
apparatus includes:a drum;a roller having a smaller diameter than the
drum;an endless belt wound around the drum and the roller;a driving power
source which transports the belt by rotating the drum; anda
line-recording recording unit placed to face an outer circumferential
surface of the drum so as to be able to perform recording with respect to
the recording medium which is laid on the outer circumferential surface
of some portion of the belt which is wound around the drum,wherein the
recording medium transported held on a surface of the belt of the
front-side image forming apparatus is delivered in a manner such that a
portion of the recording medium which has passed a position of the
recording unit is delivered over to an outer circumferential surface of a
portion of the belt which is wound around the drum at the upstream side
than the recording unit of the rear-side recording apparatus.

2. The double-sided image forming apparatus according to claim 1,wherein a
delivery portion at which the recording medium is delivered is placed in
a manner such that the recording medium is in plane contact with the
surface of each of the belts of the front-side image forming apparatus
and the rear-side image forming apparatus by a predetermined are in the
transporting direction.

3. The double-sided image forming apparatus according to claim 2,wherein
the rear-side image forming apparatus includes one drum and two
rollers;wherein the delivery portion is disposed at an area between a
roller of the front-side image forming apparatus which constitutes a
separating portion of the recording medium and a roller of the rear-side
image forming apparatus which constitutes an introduction portion of the
recording medium; andwherein an angle of the belt wound around the roller
constituting the separating portion is an acute angle and an angle of the
belt wound around the roller constituting the introduction portion is an
obtuse angle.

4. The double-sided image forming apparatus according to claim 2,wherein
transportation speed of the belt of the rear-side image forming apparatus
is higher than that of the belt of the front-side image forming
apparatus.

5. The double-sided image forming apparatus according to claim 4, further
comprising a drying unit disposed at an area between the recording unit
of the front-side image forming apparatus and the roller of the rear-side
image forming apparatus which constitutes the introduction portion of the
rear-side image forming apparatus.

6. The double-sided image forming apparatus according to claim 1,wherein a
diameter of the drum is 3 to 10 larger times than that of the roller.

7. The double-sided image forming apparatus according to claim 1, further
comprising a negative pressure unit which causes at least a portion of
the belt which is wound around the drum to adsorb the recording medium by
negative pressure.

8. The double-sided image forming apparatus according to claim 7,wherein
the front-side image forming apparatus is provided with a space disposed
at a more inner side of an inner circumferential surface of the belt and
at an outer side of the drum, in which the space is provided with a
barrier wall which demarcates a portion of the space in which adsorption
force, generated by a negative pressure generated by discharging gas out
of the drum through adsorption holes of the drum, exerts influence on the
adsorption holes of some portion of the belt, ranging from an ending
position of a winding of the belt around the drum to a beginning position
of a winding of the bent around the roller;wherein the rear-side image
forming apparatus is provided with a space disposed at a more inner side
of an inner circumferential surface of the belt and at an outer side of
the drum, in which the space is provided with a barrier wall which
demarcates a portion of the space in which adsorption force, generated by
a negative pressure generated by discharging gas out of the drum through
adsorption holes of the drum, exerts influence on the adsorption holes of
some portion of the belt, ranging from an ending position of a winding of
the belt around the drum to a beginning position of a winding of the bent
around the roller; andwherein at least a space surrounded by the barrier
wall and the belt is maintained in a sealed state.

Description:

BACKGROUND

[0001]1. Technical Field

[0002]The present invention relates a double-sided image forming apparatus
composed of a line-recording front-side image forming apparatus, such as
a line printer, and a line-recording rear-side image forming apparatus,
such as a line printer.

[0003]2. Related Art

[0004]JP-A-2003-94615 (paragraphs 0029 to 0041 and FIG. 4) discloses a
printer which records letters and/or images on recording paper using an
ink-jet recording head by attaching the recording paper to a rotating
drum and rotationally transporting the recording paper at constant speed
in order to stabilize transportation speed of the recording paper when
performing printing. This printer is provided with a grip mechanism which
holds a leading end of the recording paper. The printer is structured in
a manner such that the drum is charged by a corona charger in order to
transport the recording paper in a state in which the entire body of the
recording paper is in close contact with the drum, and the drum is
discharged by driving a separation charger as soon as the grip mechanism
releases the recording paper in order to separate the recording paper
from the drum and discharge the recording paper out of the printer. To
practically discharge the recording paper, an additional mechanism such
as a vacuum belt transport is provided in the printer.

[0005]JP-A-2005-280192 (for example, paragraphs 0013 and 0014, FIG. 2) and
JP-A-2007-76872 (for example, paragraphs 0018 to 0021, FIG. 1) disclose a
line printer (line-type ink-jet recording apparatus) in which recording
paper is transported while it is placed on a belt wound around a pair of
rollers. In such a line printer, a plurality of heads is arranged to face
a portion of an upper surface of the belt which is disposed between the
rollers. Recording by the line printer is performed by discharging ink
droplets discharged from the line heads to the recording paper which is
adsorbed to the belt in an electrostatic manner or in a negative pressure
adsorbing manner.

[0006]However, the printer disclosed in JP-A-2003-94615 has a problem in
that a large-sized structure such as the grip mechanism which grips the
leading end of the recording paper is needed. Further, the drum must be
electrically charged by the corona charger in order to transport the
entire recording paper while maintaining the recording paper to stay in a
close contact with the drum, and complicated operations are needed to
discharge the drum by driving the separation charger as soon as the grip
mechanism disengages the recording paper in order to separate and
discharge the recording paper from the drum. Further, an additional
mechanism, such as the vacuum belt transport, is also required in order
to practically discharge the recording paper. Accordingly, it is
inevitable for the entire structure of the printer become large in
volume.

[0007]In printers disclosed in JP-A-2005-280192 and JP-A-2007-76872, the
recording paper is adsorbed to the surface of the belt. However, since
the printing is performed at a position of the recording paper disposed
on the belt stretched between rollers, the belt is likely to shake and
therefore ink droplets are likely to be driven to and land on the
recording paper which is shaking. With the structure in which the belt is
stretched between rollers in the first place, it is hard to expect for
the belt and rollers which support and transport the recording paper to
have high inertia. Accordingly, speed change occurs easily. For such
reasons, positional precision of ink dots varies easily and it is
difficult to obtain high print quality.

[0008]In the case of performing double-sided recording on the recording
paper using the above-described structure, the following problems may
occur. For example, according to the former drum-type structure, two
drums are arranged to abut against each other as utilized in an offset
printer and the recording paper is delivered by the grip mechanism. In
this structure, since the two drums directly abut against each other, the
recording paper is wound around the drum used for the rear-side recording
in a state in which ink placed on the front side of the recording paper
in the front-side recording is not sufficiently dried, and therefore the
image quality of the front side deteriorates.

[0009]According to the later belt-type structure, the problem with
deterioration of the recording quality which is attributable to vibration
of the belt results in the quality deterioration of the double-sided
recording.

SUMMARY

[0010]An advantage of some aspects of the invention is to provide a
line-recording double-sided image forming apparatus which can transport a
recording medium in a relatively simple manner and achieve high precision
of recording position by stably transporting the recording medium when
performing a recording by a recording unit.

[0011]According to one aspect of the invention, there is provided a
double-sided image forming apparatus including a line-recording
front-side image forming apparatus and a line-recording rear-side image
forming apparatus, in which each of the front-side image forming
apparatus and the rear-side image forming apparatus includes a drum, a
roller having a smaller diameter than the drum, an endless belt wound
around the drum and roller, a driving source which transports the belt by
rotating the drum, and a line-recording recording unit arranged to face
an external circumferential surface of the drum so that recording is
performed to a portion of a recording medium which is placed on the
circumferential surface of the belt wound around the drum, and in which,
of the recording medium transported in a state in which it is placed on
the surface of the belt of the front-side image forming apparatus, a
portion of the recording medium having passed a position of the recording
unit is delivered in a manner such that the portion of the recording
medium is transported to the outer circumferential surface of a portion
of the belt which is wound around the drum which is at the upstream side
in the rear-side image forming apparatus by the recording unit.

[0012]The "drum" does not mean only a drum which is used in a manner such
that the recording medium is directly in contact with the surface of the
drum, the surface of the drum is used as a platen, and the recording is
performed on the surface of the drum (in a slick, curved form). That is,
the drum may be other structures in which the recording is performed on
the surface of the belt in a state in which the belt is wound around the
drum as in the known technique. For example, the drum may also be a
structure in which a shape of the surface of the drum is not slick.

[0013]With this structure, the line-recording recording unit performs the
recording with respect to the recording medium which is fed, and
particularly to a portion of the recording medium placed on the outer
circumferential surface of the portion of the belt wound around the drum.
The drum has a larger diameter than the roller. Accordingly, in the case
in which the drum rotates at constant speed, a stable rotation thereof
can be achieved. For such a reason, the portion of the recording medium
which is transported as it is placed on the drum via the belt is stably
transported without vibration, and the speed change and the recording is
performed with respect to the portion of the recording medium which is
stably transported. Accordingly, it is possible to ensure high precision
in recording positions and facilitate high quality double-sided
recording. Further, since the recording medium is transported by the
belt, the transportation mechanism for transporting the recording medium
is very simple. Since the mass of the drum affects the inertia, it is
preferable that the outer diameter of the drum is set so that the drum
more strongly affects movement of the belt than the roller when
considering in terms of the mass.

[0014]In the case in which the recording unit adopts a serial recording
system, the drum must be intermittently driven in order to intermittently
transport the recording medium. In such a case, a higher inertia brings
about deterioration of precision in stop position. However, since the
line-recording system is adopted as the recording unit, stable
transportation of the recording medium can be achieved by just rotating
the drum at constant speed during the recording, and therefore it is
possible to obtain excellent effects.

[0015]In the double-sided image forming apparatus, it is preferable that a
delivery portion at which the recording medium is delivered is designed
in a manner such that the recording medium is in plane contact with a
predetermined portion of each of the belts of the front-side image
forming apparatus and the rear-side image forming apparatus.

[0016]With this structure, the delivery portion at which delivery of the
recording medium is performed is designed to be in plane contact with a
predetermined area of the surface of each of the belts of the front-side
image forming apparatus and the rear-side image forming apparatus along
the transportation direction. Accordingly, at the delivery portion, the
recording medium is in a state in which it is supported from the upside
and the underside thereof by the belts. After this state, the recording
medium drops into a state in which it is supported only by the belt of
the rear-side recording image forming apparatus. Accordingly, the
recording medium is smoothly delivered from the upper surface of the
front-side image forming apparatus to the upper surface of the rear-side
image forming apparatus, and therefore it is possible to prevent lowering
of the recording quality which is attributable to the poor delivery.

[0017]In the double-sided image forming apparatus, it is preferable that
at least the rear-side image forming apparatus includes one drum and two
rollers; the delivery portion is disposed at an area between a roller of
the front-side image forming apparatus which forms a separation portion
of the recording medium and a roller of the rear-side image forming
apparatus which forms an introduction portion of the recording medium; an
angle of the belt, which is wound around the roller, with respect to the
roller forming the separation portion is an acute angle; and an angle of
the belt, which is wound around the roller, with respect to the roller
forming the introduction portion is an obtuse angle.

[0018]With this structure, at least the rear-side image forming apparatus
includes one drum and two rollers. Accordingly, since the image forming
apparatus has a three-axis structure, the degree of design freedom
increases and therefore it is possible to reserve a space for installing
a dry unit which will be described later and other parts. The front-side
image forming apparatus also may have a three-axis structure including
one drum and two rollers.

[0019]The deliver portion is disposed at an area between the roller of the
front-side image forming apparatus which forms the separation portion and
the roller of the rear-side image forming apparatus which forms the
introduction portion, the angle of the belt wound around the roller
forming the separation portion is an acute angle, and the angle of the
belt wound around the roller forming the introduction portion is an
obtuse angle. Accordingly, when the recording medium with the front-side
surface on which the recording is performed by the front-side image
forming apparatus approaches to the delivery portion so as to be
delivered to the rear-side image forming apparatus, even if the leading
end of the recording medium is lifted, the lifting of the recording
medium is easily corrected by the obtuse angle and the recording medium
enters the delivery portion in the corrected posture.

[0020]In the double-sided image forming apparatus, it is preferable that
transportation speed of the belt of the rear-side image forming apparatus
is higher than transportation speed of the belt of the front-side image
forming apparatus.

[0021]In typical printers, the transportation speeds of the belts of the
front-side image forming apparatus and the rear-side image forming
apparatus are equal to each other and the front-side and rear-side image
forming apparatuses are synchronously driven. Accordingly, at the deliver
portion, although the recording medium receives transportation force from
both belts, the delivery mismatching must not occur. However, in actual
practice, it is neither simple nor easy to set the speeds to be perfectly
identical. Accordingly, there can be the speed difference between both
belts. The speed difference leads to jamming.

[0022]With this structure, since the belt speeds are set such that the
transportation speed of the belt of the rear-side image forming apparatus
is higher than the transportation speed of the belt of the front-side
image forming apparatus, it is possible to prevent jamming from
occurring.

[0023]In the double-sided image forming apparatus, it is preferable that a
dry unit is disposed at an area between the recording unit of the
front-side image forming apparatus and the roller of the rear-side image
forming apparatus which forms the introduction portion.

[0024]With this structure, since the transportation speed of the belt of
the rear-side image forming apparatus is set to be higher than the
transportation speed of the belt of the front-side image forming
apparatus, contact load with respect to the recording-finished surface of
the recording medium attributable to the speed difference might increase,
but it is possible to prevent recording quality deterioration
attributable to the increase of the contact load by drying the recording
surface in advance by the recording unit.

[0025]In the double-sided image forming apparatus, it is preferable that a
diameter of the drum is three (3) to ten (10) times larger than the
roller.

[0026]With this structure, since the diameter of the drum is within a
range of 3 to 10 times of the diameter of the roller, it is possible to
avoid having the apparatus with a large volume attributable to the large
diameter of the drum. Further, since the drum has a sufficiently higher
inertia than the roller, it is possible to transport the portion of the
recording medium which is wound the drum. Accordingly, precision of the
transportation position of the recording medium is improved and it is
possible to effectively improve precision of the recording position with
respect to the recording medium.

[0027]In the double-sided image forming apparatus, it is preferable that
at least a portion of the belt which is wound around the drum has a
negative pressure unit which adsorbs the recording medium.

[0028]With this structure, at least at the portion of the belt wound
around the drum, since the recording medium is adsorbed to the upper
surface of the belt by a negative pressure generated by the negative
pressure unit, it is possible to effectively prevent position
misalignment of the recording medium with respect to the outer
circumferential surface of the drum which is stably driven from
occurring. Accordingly, it becomes easy to obtain high precision in the
recording position by effectively avoiding the position misalignment of
the recording medium with respect to the drum (or belt).

[0029]In the double-sided image forming apparatus, it is preferable that
the front-side recording apparatus has a space disposed at a more inner
side than the inner circumferential surface of the belt and disposed
outside the drum in which the space is provided with a barrier wall
portion which demarcates a portion of the space in which suction force
can be imparted to the adsorption holes of the portion of the belt
ranging from an ending point of the winding of the belt with respect to
the drum to a beginning point of the winding of the belt with respect to
the roller by the negative pressure caused by discharging the air in the
drum out of the drum through the adsorption holes of the drum; and the
rear-side recording apparatus has a space disposed at a more inner side
than the inner circumferential surface of the belt and disposed outside
the drum, in which the space is provided with a barrier wall portion
which demarcates a portion of the space in which adsorption force can be
imparted to the adsorption holes 115a of the portion of the belt ranging
from an ending point of the winding of the belt with respect to the drum
to a beginning point of the winding of the belt with respect to the
roller by the negative pressure caused by discharging the air in the drum
out of the drum through the adsorption holes of the drum; and the spaces
surrounded by at least the barrier wall portions and the belts are
sealed.

[0030]With this structure, the space disposed at more inner side than the
inner circumferential surface of the belt and disposed outside the drum
(the space inside the belt which can communicate with the drum through
the adsorption holes). Further it is possible to concentrate the negative
pressure to the adsorption holes of some portion of the belt on which the
recording medium is transported, the portion ranging from a downstream
side of the winding of the belt wound around the drum to a position of
the belt wound around the roller in the case of the front-side image
forming apparatus and the portion ranging from a downstream side of the
winding of the belt wound around the drum to a position of the belt wound
around the roller in the case of the rear-side image forming apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS

[0031]The invention will be described with reference to the accompanying
drawings, wherein like numbers reference like elements.

[0032]FIG. 1 is a schematic side-sectional view illustrating main part of
a double-sided image forming apparatus according to a first embodiment of
the invention.

[0033]FIG. 2 is a plan view illustrating a portion of a front-side
recording apparatus of FIG. 1.

[0034]FIG. 3 is a schematic side-sectional view illustrating a portion of
a front-side recording apparatus according to a second embodiment of the
invention.

[0035]FIG. 4 is a schematic side view illustrating the front-side
recording apparatus according to the second embodiment.

[0036]FIG. 5 is a schematic side plan view illustrating the front-side
recording apparatus according to the second embodiment.

[0037]FIG. 6 is a schematic side-sectional view illustrating part of a
double-sided image forming apparatus according to a third embodiment of
the invention.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

First Embodiment

[0038]Hereinafter, embodiments of the invention will be described with
reference to the accompanying drawings FIG. 1 and FIG. 2.

[0039]FIG. 1 shows a double-sided image forming apparatus including an
ink-jet, line-recording front-side recording apparatus and an ink-jet,
line-recording rear-side recording apparatus. FIG. 2 shows a portion of
the front-side recording apparatus of FIG. 1. In FIG. 1, a direction from
a lower position to a left position and from the left position to a right
position is a transportation direction of paper. FIG. 2 shows a state in
which recording paper is in a transportation position after printing
begins.

[0040]As shown in FIG. 1, the double-sided image forming apparatus
according to this embodiment includes a line-recording front-side
recording apparatus 1 and a line-recording rear-side recording apparatus
2 which are arranged in a transportation direction of recording paper P.
In this embodiment, the front-side recording apparatus 1 and the
rear-side recording apparatus 2 basically have the same structure as each
other. The basic structure will be described below.

[0041]As shown in FIGS. 1 and 2, a line printer (simply referred to as
printer 11) serving as the front-side recording apparatus 1 includes a
belt transportation apparatus 12 for transporting the recording paper P.
The belt transportation apparatus 12 includes a driving drum disposed at
an upstream side in the paper transportation direction (referred to as
drum 13), a driven roller disposed at a downstream side in the paper
transportation direction (referred to as roller 14), and an endless
transportation belt engaging the drum 13 and the roller 14 (referred to
as belt 15). Rotation shafts 13a and 14a of the drum 13 and the roller 14
are rotatably supported by bearings.

[0042]The drum 13 has the same surface form and diameter as the
known-structured drum in which the surface of the drum is in direct
contact with the recording paper P and recording is performed on the
surface (in slick and curved form) of the drum as using the surface of
the drum as a platen. Alternatively, the structure of the drum 13 may not
be limited thereto. That is, the drum may have any structures as long as
the structure enables the recording, which was performed on the drum
surface having the slick curved shape, to be performed on the surface of
the belt 15 which is wound around the drum 13 because the belt 15 is
wound around the drum 13. Accordingly, the drums of which the surfaces
are not slick can also be used.

[0043]The drum 13 is connected to an output shaft of an electric motor 16
shown in FIG. 2 directly or via a decelerating mechanism (not shown) so
that driving force can be transferred. When the electric motor 16 which
is a driving power source is driven forward, the drum 13 is rotated and
therefore the belt 15 rotates the recording paper P in the transportation
direction from the upstream side to the downstream side. A pair of gate
rollers 17 constituting a paper feeding unit is disposed at a proximal
position under the drum 13 at the upstream side in the transportation
direction in the belt transportation apparatus 12. The recording paper P
is fed to the upper surface of the belt 15 wound around the drum 13 by
the gate rollers 17.

[0044]The gate rollers 17 correct the skew of the recording paper P by
causing the recording paper P to strike the surface of the rollers, and
sends the recording paper P so that the recording paper P is placed on a
target position on the belt 15 at proper timing by adjusting drive start
timing. For example, the belt 15 is an endless type in which both ends of
a belt-like member are connected to each other, and the recording paper P
is sent not to poke the seam of the belt 15.

[0045]The belt 15 is made of rubber. The belt 15 can maintain the
recording paper P thereon because the surface of the belt made of rubber
has adherence. It is possible to maintain the recording paper P at the
surface of the belt 15 by a known electrostatic adsorption manner or a
negative pressure adsorption manner.

[0046]Four line-recording recording heads (line heads 19Y, 19M, 19C, and
19K) serving as the recording units are placed to face the outer
circumferential surface of the drum 13 at the outer and upper position of
the drum 13, and arranged along the outer circumferential surface of the
drum 13 at a regular gap between them. The four line heads 19Y, 19M, 19C,
and 19K discharge four colors of ink droplets, yellow Y, magenta M, cyan
C, and black K. The ink to be discharged is supplied through an ink
supply tube from each of ink tanks (not shown).

[0047]Each of the line heads 19Y, 19M, 19C, and 19K has a length by which
recording can be performed over the maximum width of the paper, and a
plurality of nozzles is arranged in a direction (nozzle column direction)
which intersects the transportation direction of the recording paper P.
Fine ink dots are formed on the recording printer P by simultaneously
discharging ink droplets of the desired amount to desired positions from
the nozzles. As such an operation is performed for each of colors, it is
possible to record letters and images onto the recording paper P in one
pass in which recording is performed by causing the recording paper P on
the belt 15 to pass through a transportation path between each of the
line heads 19Y, 19M, 19C, and 19K and the belt 15 just once.

[0048]The number of needed colors of line heads 19Y, 19M, 19C, and 19K may
be structured in a single head form or as a multi-head form in which a
plural number of unit heads is arranged in a line form in a direction
which intersects the transportation direction so that the whole of the
line heads 19Y, 19M, 19C, and 19K serve like a single line head. The
plural number of unit heads is positioned at different places in a
direction (paper width direction) which intersects the transportation
direction. Alternatively, at least some of the unit heads may be placed
at different positions in the transportation direction as long as the
printing can be performed over the entire width of the paper by the
plural number of unit heads. In the case of indiscriminating ink colors,
the line heads 19Y, 19M, 19C, and 19K may be inscribed by a line head 19
in the lump.

[0049]As shown in FIG. 2, a magnetic linear encoder 20 is disposed at a
side edge of the belt 15. The magnetic linear encoder 20 is composed of a
magnetic linear scale 21 formed over the whole circumference of a belt
and a magnetic sensor 22 which detects and reproduces magnetic patterns
with magnetized portions with a predetermined pitch therebetween on the
surface of the magnetic linear scale 21. The magnetic sensor 22 outputs
an encoder signal (pulses) composed of a number of pulses which is
proportional to rotation amount of the belt 15. The controller 23 serving
as a control unit disposed in the printer 11 controls the electric motor
16 to rotate at constant speed according to a recording mode on the basis
of the encoder signal output from the magnetic sensor 22. Further, the
controller 23 controls the recording head so that the recording head
ejects ink droplets at proper timing which is set to match with a paper
transportation position on the basis of recording reference pulse
(ejection timing signals) generated on the basis of the encoder signal in
an internal circuit.

[0050]FIGS. 1 and 2 schematically show a ratio of a diameter of the drum
13 to a diameter of the roller 14. Practically, the drum 13 according to
this embodiment has a diameter which is larger 3 to 10 times larger than
the diameter of the roller 14. For example, when the diameter of the
roller is 3 cm, it is preferable that the diameter of the drum 13 is 9 to
30 cm. Such a diameter ratio is set in order to stably rotate the drum 13
while ensuring the high inertia by increasing the diameter of the drum 13
and to securely reserve an arrangement area for the line heads 19Y, 19M,
19C, and 19K which perform a printing on the outer circumferential
surface of the drum.

[0051]Further, since mass of the drum 13 affects the inertia, it is
preferable that the outer diameter of the drum 13 is set such that the
drum 13 more significantly affects operation of the belt 15 than the
roller 14.

[0052]When the recording paper P is transported along the surface of the
belt 15 and reaches the roller 14, the recording paper P must be
separated from the surface of the belt 15. With this example, however,
the recording paper P is separated by its intrinsic stiffness and a
curvature of a portion of the belt 15 wound around the roller 14. The
curvature of the belt 15 is determined to achieve curvature separation of
the recording paper P by the stiffness of the recording paper P and the
diameter of the roller 14 is determined to obtain such curvature.
Separation pawls 24 for compulsively separating the recording paper P are
placed at a relatively downstream side position in the transportation
direction in comparison with a position at which curvature separation of
the recording paper P occurs. A plurality of the separation pawls 24 is
disposed in parallel with one another in the width direction of the belt
15, and the recording paper P is separated from the belt 15 when a
portion of the recording paper P, which is not separated by curvature
separation, and comes into contact with the plurality of pawls arranged
in the paper width direction. Alternatively, the separation pawls 24 may
be disposed at a position where the curvature separation of the recording
paper P occurs.

[0053]Next, the line printer (hereinafter, referred to as a printer 111)
serving as the rear-side recording apparatus 2 is equipped with a belt
transportation apparatus 112 having the same structure as the belt
transportation apparatus of the front-side recording apparatus 1. The
belt transportation apparatus 112 includes a driving drum (hereinafter,
referred to as a drum 113) disposed at an upstream side in the paper
transportation direction, a driven roller (hereinafter, referred to as a
roller 114) disposed at a downstream side in the paper transportation
direction, and an endless transportation belt (hereinafter, simply
referred to as a belt 115) wound around the drum 113 and the roller 114
to run from the drum 113 to the roller 114. Rotation shafts 113a and 114a
of the drum 113 and the roller 114 are supported by bearings (not shown)
in a rotatable manner.

[0054]The rear-side recording apparatus is further equipped with line
heads 119Y, 119M, 119C, and 119K corresponding to the line heads 19Y,
19M, 19C, and 19K, and pawls 124 corresponding to the pawls 24 in the
front-side recording apparatus. The line printer is still further
equipped with an electric motor and a magnetic linear encoder (magnetic
linear scale and a magnetic sensor) which correspond to the electric
motor 16, the magnetic linear encoder 20 (magnetic linear scale 21 and
magnetic sensor 22), and the controller 23.

[0055]As shown in FIG. 1, a portion of the recording paper P transported
in a state in which it is maintained on the surface of the belt 15 of the
front-side recording apparatus 1 passes positions of the line heads 19Y,
19M, 19C, and 19K, and the portion of the recording paper P is delivered
such that it moves along the outer circumferential surface of the belt
115 wound around the drum 113 disposed at the upstream side of the line
heads 119Y, 119M, 119C, and 119K.

[0056]When the recording begins in the double-sided image forming
apparatus (the front-side recording apparatus 1 and the rear-side
recording apparatus 2) having the above-described structure, the
recording paper P is fed to the surface of the drum 13 disposed at the
upstream side of the transportation direction in the front-side recording
apparatus 1 of FIG. 1 by the gate rollers 17. The recording paper P is in
close contact with (attached to) the upper surface of the belt 15 by
adherence of the surface of the belt 15.

[0057]The belt 15 is driven by the force of the drum 13 at the driving
side, and the belt 15 revolves along the movement of the drum 13. Since
the movement of the belt 15 on the drum 13 depends on the drum 13,
movement of the recording paper P placed on the belt also depends on the
drum 13. Here, when the drum 13 having a high inertia rotates at constant
speed, the drum 13 stably rotates. Even if the speed change occurs at the
driven roller side, rotation of the belt 15 on the drum 13 is stable,
which it not likely to result in vibration of the belt 15. Accordingly,
belt transportation is also considerably stable, contributing to high
quality in fast printing.

[0058]Orientation of the belt 15 depends on the drum 13 having a larger
winding amount of the drum 13 and the roller 14. Accordingly, even if the
speed change occurs at the driven roller side having a smaller diameter,
revolving of the belt 15 is stable and meandering of the belt is unlikely
to occur.

[0059]Although the belt 15 meanders toward the drum 13 and the belt is
disposed between the recording paper P and the drum 13, the recording
paper 13 eventually rotates by the rotation of the drum. That is,
although the belt 15 meanders toward the drum 13 and the recording paper
P is placed on the belt 15 while inclining with respect to the belt 15,
since the recording paper P is placed without inclination with respect to
the drum 13, if the recording paper P is supplied to the surface of the
drum 13 in a right posture at a right position, even if the belt 15 on
which the recording paper P is placed meanders, the recording paper is
stably transported along the rotation of the drum 13.

[0060]Since the line printer 11 which is the front-side recording
apparatus 1 has a structure in which the recording is performed by a
line-recording line head 19, the recording to the surface of the
recording paper P progresses while the drum 13 rotates at constant speed.
If a serial recording method is adopted, every when a serial recording
head is moved in a thrust direction of the drum for scanning, driving and
stopping of the drum having a high inertia are repeated and precision of
stop positions of the drum deteriorates. In the case of the line head,
since the recording can be performed while the drum 13 rotates at
constant speed, precision of transportation position of the recording
paper P is raised and high quality recording can be performed on the
recording paper P by the stable rotation of the drum 13. At this time,
the recording is performed fast and printing for a sheet of paper is
finished only by a single time of rotation of the drum 13 or two times of
rotations of the drum 15 (for example, within 1 to 5 seconds).

[0061]The recording paper P having the surface, on which a recording is
performed by the line heads 19Y, 19M, 19C, and 19K, is transported while
it is placed on the belt 15 at a position corresponding to the roller 14
positioned at the downstream side of the transportation direction of FIG.
1, is separated by curvature separation thanks to the curved surface of
the belt 15 at which the curvature of the drum sharply changes according
to the diameter of the roller 14, and is delivered to the rear-side
recording apparatus 2. The recording paper P is separated (curvature
separation) from the belt 15 only by its stiffness which causes the
recording paper P attached to the belt 15 to be bent and therefore the
recording paper P is separated from the belt 15. Even if some portion of
the recording paper P is not separated by curvature separation, the
portion can be separated by the separation pawls 24.

[0062]As shown in FIG. 1, the printer is structured in a manner such that
some portion of the recording paper P, which is delivered to the
rear-side recording apparatus 2, is transported to the outer
circumferential surface of the belt 115 wound around the drum 113
disposed at the upstream side of the line heads 119Y, 119M, 119C, and
119K in the rear-side recording apparatus 2. The recording paper P with a
rear surface on which the recording is performed by the line heads 119Y,
119M, 119C, and 119K is transported while it is placed on the belt 115 at
a position corresponding to the roller 114 at the downstream side of the
transportation direction of FIG. 1. Then the recording paper P is
separated in a curvature separation manner by the curved surface of the
belt 15 of which the curvature sharply changes according to the diameter
of the roller 114, and is finally discharged out of the printer by being
separated by the separation pawls 124.

[0063]According to the above-described first embodiment of the invention,
it is possible to obtain the following advantages.

[0064](1) Since the recordings by the line head 19 and 119 are performed
to the recording paper P which is supplied and particularly to a portion
of the recording paper P which is disposed on the drums 13 and 113 having
a large diameter and high inertia and rotating stably, it is possible to
perform the recording with high precision in recording positions. Since
the recording units are the line heads 19 and 119, the recording
progresses while the drums 13 and 113 are rotated at constant speed.
Accordingly, such a structure results in improvement of the precision in
the recording positions. For example, if the recording is performed by a
serial recording method, the drum must be intermittently driven. Since
the precision of stop positions of the drum having high inertia
(precision in paper transportation position) is lowered, recording
precision is also lowered. On the other hand, since the recording is
performed by the line recording method, the drums 13 and 113 having high
inertial may be continuously rotated at constant speed without stopping
which causes deterioration of the precision of the recording position in
the middle of recording. Accordingly, it is possible to achieve stable
rotation of the drum and to ensure high precision of the recording
position.

[0065](2) Since the belts 15 and 115 are used for transporting the
recording paper P, the transportation of the recording paper P can be
achieved by the belts 15 and 115 in a simple manner. Further, although
the recording paper P is indirectly placed on the drums 13 and 113 via
the belts 15 and 115 rather than directly placed on the outer
circumferential surfaces of the drums 13 and 113, some portion of each of
the belts 15 and 115 wound around the outer circumferential surface of
each of the drums 13, 113 moves along the motion of each of the drums 13
and 113. Accordingly, it is possible to achieve stable transportation of
the recording paper P and therefore to perform high quality recording.

[0066](3) Since each of the rollers 14 and 114 having a smaller diameter
and each of the drum 13 and 113 form a pair of rotating bodies around
which each of the belts 15 and 115 is wound, the recording paper P
transported in a state in which it is placed on the belts 15 and 115
after the recording is performed can be separated from the belts 15 and
115 (by curvature separation) at a curved portion of the belt at which
the curvature is high in a simple manner, corresponding to the roller 14,
114. For example, the plurality of grip mechanisms provided for
separating the recording paper from the drum disclosed in JP-A-2003-94615
is not needed.

[0067](4) Since the diameter of the drums 13 and 113 is set to have a
value in a range from 3 to 10 times the diameter of the rollers 14 and
114, it is possible to ensure relatively sufficient inertia of the drums
13 and 113 in comparison with the rollers 14 and 114 while avoiding
increasing the size of the printers 11 and 111 attributable to the large
size of the drums 13 and 113, and therefore it is possible to realize
transportation stability of the recording paper P and improvement of the
precision of the recording position with respect to the recording paper
P.

[0068](5) Although a portion of each of the belts 15 and 115 which is
stretched between each of the drums 13 and 113 and each of the rollers 14
and 114 vibrates or each of the belts 15 and 115 shakes at a
predetermined period according to speed change, attributable to the speed
change of the rollers 14 and 114 having relatively low inertia, various
kinds of vibration and shaking are not transferred to a portion of the
recording paper P wound around the drums 13 and 113. Accordingly, such a
structure contributes to improvement of the recording quality in the
double-sided recording.

Second Embodiment

[0069]Next, a double-sided image forming apparatus according to a second
embodiment will be described with reference to the accompanying drawings
FIG. 3 to FIG. 5.

[0070]FIG. 3 is a schematic side-sectional view illustrating a front-side
recording apparatus of the double-sided image forming apparatus according
to the second embodiment, FIG. 4 is a schematic side view, and FIG. 5 is
a plan view illustrating the front-side recording apparatus. Since the
rear-side recording apparatus of the double-sided image forming apparatus
according to the second embodiment basically has the same structure as
the front-side recording apparatus, illustration and description thereof
will be omitted.

[0071]The double-sided image forming apparatus according to the second
embodiment is different from the first embodiment from a point of view in
which the negative pressure adsorption with respect to the belt is
adopted.

[0072]A drum 13 in a line printer (hereinafter, simply referred to as
printer 31) serving as the front-side recording apparatus 1 is shown in
FIG. 3 provided with a plurality of adsorption holes 13b. The adsorption
holes 13b in dot form are distributed over the entire area of the outer
circumferential surface of the drum 13. The belt 15 is also provided with
a plurality of adsorption holes 15a having a dot form over the entire
area thereof. As for some portion of the belt 15 wound around the drum
13, even if the winding position of the belt 15 is slightly deviated from
the corresponding position of the drum 13, at least some of the
adsorption holes 13b at the drum 13 side and the adsorption holes 15a at
the belt 15 side communicate with one another. For example, since the
adsorption holes 13b and 15a are randomly formed in each of the drum 13
and the belt 15, or the adsorption holes of either the drum 13 or the
belt 15 are sufficiently larger than the adsorption holes of the other
one.

[0073]As shown in FIG. 4 and FIG. 5, both sides of the printer 11 (both
sides in a direction which intersects the surface of paper of FIG. 4) are
closed by left and right side plates 32 so that air does not leak from
the printer except from a portion through which air is discharged from
the drum 13. Gap between the side plates 32 and movable parts, such as
the drum 13, the roller 14, and the belt 15 is sealed using known sealing
means, such as a contact seal or a labyrinth structure.

[0074]As shown in FIG. 5, one end of a pipe 33 which communicates with the
inside of the drum 13 is connected to either one of the side plates 32
(at an upper side of FIG. 5) and the other end of the pipe 33 is
connected to a fan 34. Since the fan 34 is driven and rotated by the
controller 23, air in a drum chamber 35 inside the drum 13 is vacuumed
and discharged out of the drum chamber 35 and the inside of the drum 13
is maintained at a negative pressure. A belt chamber 36 which is a closed
spaced surrounded by the belt 15, the left and right side plates 32, the
drum 13, and the roller 14 communicates with the inside of the drum 13
via the adsorption holes 13b. Accordingly, when the drum 13 is in a
negative pressure state, the inside of the belt 36 also becomes the
negative pressure state.

[0075]Air current which directs toward the belt chamber 36 from the outer
circumferential surface side of the belt 15 flows through the adsorption
holes 15a of the belt 15 by the negative pressure of the inside space of
the belt chamber 36, and the recording paper P is transported after the
recording is performed in a state in which the recording paper P is
adsorbed to the upper surface of an upper portion of the belt 15.
Accordingly, of the recording paper P, a portion of the recording paper
P, which is transported in a state in which the recording paper is placed
on the belt 15 after the recording is performed, is stably transported
while the recording paper P does not wind up from the upper surface of
the belt 15 although it is exposed to the air current (wind) with
predetermined force of wind. For such a reason, some portion of the
recording paper P on which the recording is finished winds up from the
belt 15, and some portion of the recording paper on which the recording
is being performed and the other portion of the recording paper on which
the recording is to be performed may not be misaligned with the drum 13.

[0076]The printer has a structure in which the recording paper P is
adsorbed to the upper surface of the belt 15. Further, since the
recording paper P can be placed on the adsorbing surface of the belt 15
which is at the lower side of the gravity direction, the gate rollers 17
are placed at the lower side of the drum 13 than the placement position
of the first embodiment. As a result, the paper feeding position of the
recording paper P with respect to the drum 13 is shifted to a
sufficiently lower side on the outer circumferential surface of the drum
13, the winding amount of the recording paper P, which is wound around
the drum, in the circumferential direction of the drum 13 is increased.

[0077]In the printer 11, air is discharged out of the drum 13 by driving
the fan 34 and air current which directs toward an inner circumferential
side from an outer circumferential side of the adsorption holes 13b and
15a which are openings formed in the drum 13 and the belt 15 is created.
Accordingly, the recording paper P is transported while it is adsorbed
onto the surface of the belt 15. With such a structure, since the problem
with position misalignment between the recording paper P and the drum 13
is solved, it is possible to achieve stable transportation of the
recording paper P.

[0078]When the recording paper P is transported to a position
corresponding to the roller 14 positioned at the downstream side of the
transportation direction (at the left side of FIG. 3), the adsorption
holes 15a in the portion of the belt wound around the roller 14 are
closed by the outer circumferential surface of the roller 14 and
therefore adsorbing force cannot reach the recording paper P on the belt
15. Accordingly, it is possible to easily separate the recording paper P
from the belt 15 by the decreased adsorbing force attributable to the
closed state of the adsorption holes 15a and the curvature separation by
the roller 14. As in the first embodiment, since the separation pawls 24
are provided, even if there is some portion of the recording paper P,
which has not been separated by the curvature separation, the unseparated
portion can be surely separated by the separation pawls 24.

[0079]According to the second embodiment, the following advantages can be
obtained.

[0080](6) The inside of the drum 13 comes to have a negative pressure by
the drive of the fan 34, and the recording paper P is adsorbed to some
portion of the surface of the belt 15 which is wound around the drum 13
thanks to the adsorption holes 13b and 15a formed in both of the drum 13
and the belt 15. Accordingly, it is possible to surely avoid the
positional misalignment between the drum 13 and the recording paper P.
Accordingly, it is possible to maintain high precision of recording
position with respect to the recording paper P.

[0081](7) Since the belt chamber 36 which communicates with the inside of
the drum 13 (drum chamber 35) through the adsorption holes 13b becomes a
negative pressure, it is possible to transport the recording paper P in a
state in which the recording paper P is adsorbed to the surface of the
belt 15 after the recording is finished. However, at the portion of the
recording paper P which is separated from the belt by the curvature
separation, the recording paper P can be easily separated from the belt
by the curvature separation since the adsorption holes 15a of the belt 15
are closed by the outer circumferential surface of the roller 14 and
therefore the adsorbing force cannot be imparted to the recording paper P
on the belt 15.

[0082](8) Since the recording paper P is adsorbed to the surface of the
belt 15, it is possible to place the recording paper P even on the
adsorbing surface which is the lower side of the belt 15 in the gravity
direction, and therefore it is possible to increase winding amount of the
belt 15 and the recording paper P with respect to the outer
circumferential surface of the drum 13 in the circumference direction of
the drum 13. Accordingly, it is possible to increase an area of the outer
circumferential surface of the drum 13 at which the drum 13 and the line
heads 19 face each other and the recording paper P is wound around.
Accordingly, it is possible to respond to the need for arrangement of a
plural number of line heads 19 so as to correspond to five or more
colors, and also it is possible to improve the degree of freedom when
selecting the arrangement of the line heads 19 in the case in which the
number of the line heads is small.

Third Embodiment

[0083]Next, a double-sided image forming apparatus according to a third
embodiment of the invention will be described with reference to FIG. 6.
FIG. 6 is a schematic side sectional view illustrating the double-sided
image forming apparatus according to the third embodiment.

[0084]As shown in FIG. 6, the double-sided image forming apparatus
according this embodiment is equipped with a line-recording front-side
recording apparatus 1 and a line-recording rear-side recording apparatus
2 which are arranged in the transportation direction of the recording
paper P like the above-mentioned embodiments. With this embodiment, both
of the front-side recording apparatus 1 or the rear-side recording
apparatus 2 may have a structure of including one drum 13, 113 and two
rollers. That is, the front-side recording apparatus 1 includes a first
roller 14a and a second roller 14b and the rear-side recording apparatus
2 includes a first roller 114a and a second roller 114b. That is, both of
the front-side recording apparatus 1 and the rear-side recording
apparatus 2 have a three-axis structure.

[0085]A delivery portion 4 at which the recording paper P is delivered is
structured such that the surface of each of the belts 15 and 115 of the
front-side recording apparatus 1 and the rear-side recording apparatus 2
is placed to be in direct plane contact with the recording paper P by a
predetermined area in the transportation direction.

[0086]The delivery portion 4 is disposed at an area between the roller 14a
of the front-side recording apparatus 1 which constitutes a separation
portion 6 of the recording paper P and the roller 114b of the rear-side
recording apparatus 2 which constitutes an introduction portion 8 of the
recording paper P. An angle θ1 of the belt 15 wound around the
roller 14a which constitutes the separation portion 6 is an acute angle
with respect to the roller 14a, and an angle θ2 of the belt wound
around the roller 114b which constitutes the introduction portion 8 is an
obtuse angle with respect to the roller 114b.

[0087]With this embodiment, belt transportation speed V2 of the rear-side
recording apparatus 2 is slightly faster than belt transportation speed
V1 of the front-side recording apparatus 1. A halogen lamp serving as dry
means 61 is disposed at an area between the line head 19 of the
front-side recording apparatus and the roller 114b of the rear-side
recording apparatus 2 which constitutes the introduction portion 8.
Another dry means 62 is disposed at the downstream side of the drum 113.
Instead of the halogen lamp, the dry means 61 may be constituted as an
optical dry machine, such as a xenon lamp, a mercury lamp or a LED lamp
which emits ultraviolet rays which cures UV-curable ink, heat of
radiation, air of room temperature, and hot air of 60 to 250° C.

[0088]In the front-side recording apparatus 1, a space 47 disposed at a
more inner side than the inner circumferential surface of the belt 15 and
disposed outside the drum 13 is provided with a barrier wall portion 63
which demarcates a portion of the space 47 in which adsorption force can
be imparted to the adsorption holes 15a of the portion of the belt 15
ranging from an ending point of the winding of the belt 15 with respect
to the drum 13 to a beginning point of the winding of the belt 15 with
respect to the roller 14a by the negative pressure caused by discharging
the air in the drum 13 out of the drum 13 through the adsorption holes
13b of the drum 13. In the rear-side recording apparatus 2, a space 147
disposed at a more inner side than the inner circumferential surface of
the belt 115 and disposed outside the drum 113 is provided with a barrier
wall portion 64 which demarcates a portion of the space 147 in which
adsorption force can be imparted to the adsorption holes 115a of the
portion of the belt 115 ranging from an ending point of the winding of
the belt 115 with respect to the drum 113 to a beginning point of the
winding of the belt 115 with respect to the roller 114b by the negative
pressure caused by discharging the air in the drum 113 out of the drum
113 through the adsorption holes 113b of the drum 113. The spaces 47 and
147 surrounded by at least the barrier wall portions 63 and 64 and the
belts 15 and 115, respectively are sealed.

[0089]A position behind the delivery portion 4 is provided with the paper
leading end detector 65. Since the leading end of the recording paper
with the front-side surface on which the recording has been already
performed by the front-side recording apparatus 1 is detected by the
paper leading end detector 65, the recording paper P can be sent to a
recording area of the rear-side recording apparatus 2, and it is possible
to perform the rear-side recording with high precision of the recording
position.

[0090]According to the third embodiment, the following advantages can be
achieved.

[0091]According to this embodiment, the delivery portion 4 of the
recording paper P is placed in a manner such that the recording paper P
is in plane contact with the surface of each of the belts 15 and 115 of
the front-side recording apparatus 1 and the rear-side recording
apparatus 2 in the transportation direction. Accordingly, the recording
paper P is in a state in which it is supported by the belts 15 and 115
from both of the front side and the rear side thereof at the delivery
portion 4, and then falls to a state in which it is supported only by the
belt 115 of the rear-side recording apparatus 2. Therefore, the recording
paper P is smoothly delivered to the belt 115 of the rear-side recording
apparatus 2 from the belt 15 of the front-side recording apparatus 1, and
it is possible to prevent the recording quality from deteriorating which
is likely to occur in the middle of delivering.

[0092]Further, since the rear-side recording apparatus 2 has a three-axis
structure in which a number of the drum 113 is one and a number of the
rollers 114a and 114b is two, the degree of design freedom in the entire
structure is increased, and it is possible to easily reserve a space for
installing various members, such as the dry means 61 and the paper
leading end detector 65 therein.

[0093]Further, the delivery portion 4 is provided at an area between the
roller 14a of the front-side recording apparatus 1 which constitutes a
separation portion 6 and the roller 114b of the rear-side recording
apparatus 2 which constitutes an introduction portion 8 of the recording
paper P, an angle of the belt wound around the roller 14a which
constitutes the separation portion 6 is an acute angle with respect to
the roller 14a, and an angle θ1 of the belt wound around the roller
114b which constitutes the introduction portion is an obtuse angle with
respect to the roller 114b. Accordingly, when the recording paper P with
the front-side surface on which the recording is finished by the
front-side recording apparatus 1 is transported toward the rear-side
recording apparatus 2 and approaches the delivery portion 4, even if a
leading end of the recording paper P is lifted, the lifting of the
recording paper P is easily corrected by the obtuse angle structure, and
then the recording paper P enters the delivery portion 4. At an exit
portion of the delivery portion 4, the recording paper P can be smoothly
moved in a state in which it is supported only by the belt 115 of the
rear-side recording apparatus 2.

[0094]Further, since the belt transportation speed V2 of the rear-side
recording apparatus 2 is slightly faster than the belt transportation
speed V1 of the front-side recording apparatus 1, it is possible to
prevent occurrence of undesirable jamming attributable to the difference
between the transportation speeds of both belts (including the reversed
relationship between the transportation speeds of both belts).

[0095]With this embodiment, the belt transportation speed V2 of the
rear-side recording apparatus 2 is faster than the belt transportation
speed V1 of the front-side recording apparatus 1. Accordingly, contact
load to the surface of the recording paper on which the recording is
finished is increased on the basis of the speed difference. However,
since the recorded surface of the recording paper have been dried already
by the dry means 61, it is possible to prevent deterioration of the
recording quality which is attributable to the increase of the contact
load.

[0096]According to this embodiment, since a space 47, 147 which is
disposed at the inner side than the outer circumferential surface of the
belt 15, 115 and disposed outside the drum 13, 113 is divided by a
barrier wall portion 63, 64, it is possible to concentrate the negative
pressure to the adsorption holes 15a of some portion of the belt 15,
ranging from a position at the downstream side of the drum 13 to a
position at which the belt 15 is wound around the roller 14a in the
front-side recording apparatus 1, and to the adsorption holes 115a of
some portion of the belt 115, ranging from a position at the down stream
side of the drum 113 to a position at which the belt 115 is wound around
the roller 114b in the rear-side recording apparatus 2. Accordingly, it
is possible to smoothly perform the delivery of the recording paper P.

Other Embodiments

[0097]The double-sided image forming apparatus according to the invention
is not limited to the ink-jet printer but may be applied to a thermal
transfer printer, or to a copying machine.

[0098]The liquid ejection type image forming apparatus is not limited to
the ink-jet type printer. The liquid ejection type image forming
apparatus can be embodied to a fluid ejection apparatus which ejects and
discharges liquids as well as ink (liquid, liquid material in which
functional material powder is mixed, fluid such as gel, and solid which
can flow and be ejected as liquid (for example, powder such as toner).
For example, the invention may be applied to a liquid material ejection
apparatus which discharges a liquid material containing an electrode
material or a color material (pixel material) used for manufacturing a
liquid crystal display, an electroluminescence (EL) display, and a
surface light emission display in a dispersed form or a dissolved form, a
liquid ejection apparatus which discharges a transparent resin solution
such as ultraviolet-curable resin for forming fine semispherical lenses
(optical lenses) used in optical communication elements on a substrate, a
liquid ejection apparatus for ejecting an etching solution, such as acid
or base used for etching a substrate, and a liquid ejection apparatus
which ejects a liquid material, such as gel (for example, physical gel).
Like each of these apparatuses, a predetermined pattern (wiring pattern,
electrode pattern, pixel pattern, etching pattern, and arrangement
pattern) formed by driving the ejected liquid to the recording medium,
such as substrate is contained in an image formed by the recording. The
"fluid" is a term containing a fluid composed of only gas and includes
liquid (inorganic solvent, organic solvent, solution, liquid-state resin,
liquid-state metal (melted metal)), power, and fluid material.